This is a grant renewal for studies on formulations of high molecular weight agents, such as proteins and nucleic acids. For the past 29 years, this particular grant has been central for our drug delivery research. We believe the impact of our NIH funded research in this area has been significant and that our work has helped provide some of the fundamental concepts necessary for the clinical development of controlled release of macromolecules and for localized drug delivery. Examples of such delivery systems are Lupron Depot, Gliadel and Nutropin Depot. In writing our last competing renewal grant proposal we felt that much of the fundamentals of peptide and protein release had been established and that the greatest impact could come from extending our research nucleic acid delivery. Our studies in this area have led to a greater mechanistic understanding, and have resulted in 35 peer-reviewed papers, including in such journals such as Science and Nature. The major barrier to the success of gene therapy in the clinic is the lack of safe and efficient DNA delivery methods. Modified viruses, while effective at transferring DNA to cells, suffer from serious toxicity and production problems. In contrast, non-viral systems offer a number of significant potential advantages, including ease of production, stability, low toxicity, and reduced vector size limitations. From our studies we have discovered that optimal intracellular delivery to different tissues in the body requires different materials. Therefore, we propose to develop combinatorial libraries of new materials with the specific goal of generating clinically useful, non-viral methods for gene therapy. Lung cancer will be used as a model disease. We propose to explore two complementary approaches: 1) developing lung-tumor cell specific DNA delivery systems for the anti-tumor therapy and 2) developing anti-lung cancer DNA vaccines by targeting and activating native immune cells. Our specific aims are: 1. To develop next-generation biodegradable polymers for use as efficient and non-toxic vectors for lung cancer and DNA vaccines. 2. Development of cell specific DNA delivery systems for lung tumor and dendritic cell targeting. 3. To test the in vivo gene delivery efficiency of biodegradable vectors composed of PEI- and PBAE- based polymer and that of their electrostatic ligand coated ternary polyplexes in normal and lung cancer mouse models. 4. To examine potential of PEI- and PBAE- based vectors for their use as DNA vaccines.